1. Field of the Invention
The present invention relates to a video camera, and more particularly to a video camera for use in combination with a video recorder.
2. Description of the Prior Art
Video recording systems utilizing the combination of a video camera and a video recorder have become ever more popular in recent years.
Among such systems, most of the compact video recording system utilizing cassette-type video tape recorders are so structured that the electric circuits in the video camera are powered by a power source in the recorder or an external power source and the recorder is brought to a stand-by state for recording when the camera is connected to the recorder or when a power supply button or a recording button on the recorder is actuated after it is connected to the camera, and that, in response to the actuation of a trigger button on the camera in this state, the camera releases a recording start signal to the recorder to initiate the function thereof, thus recording the video output signal from the camera on the magnetic tape in the recorder.
Such power supply to the camera circuits initiated simultaneously with the stand-by state of the recorder is adopted for enabling recording to start at any moment, in consideration of the fact that the imaging tube employed in the video camera requires a relatively long pre-heating time, generally in the order of 30 seconds from commencement of power supply, before reaching a stable function state.
On the other hand, the automatic focusing of the picture-taking lens is being introduced into the photographic still cameras and 8 mm movie cameras, and is being actively investigated for application also in the video cameras. However such automatic focusing device, if introduced into the video recording system as explained in the foregoing, will encounter certain difficulties. Because of the photoelectric detector means generally employed in the automatic focusing devices, the period required for accurately focusing the lens to the object significantly depends on the picture taking conditions, particularly the conditions of the object, and becomes considerably long when the conditions of the object are not favorable. Consequently, if such automatic focusing device is incorporated in the video camera, the initial portion of a scene will tend to be deteriorated since a certain period will be required for focusing the lens to the object after the trigger button is actuated for taking the scene.